Redshift schema migration

Indexes, foreign keys, primary keys, and arrays are not supported in Redshift. The distribution key, which determines how your data is distributed across the cluster, is a very important part of the schema definition. Check all queries for the table and choose the column that gets joined most frequently for the distribution key to get the best performance. You can only specify one distribution key and if you are joining against multiple columns on a large scale, you might notice a performance degradation. Also, specify the columns your range queries use the most as sort key on your table (can be multi columns in sort key), as it will help with the performance.

Oracle Database on EC2 HA environment

Oracle Data Guard can be used to set up one or several slave databases which will be the foundation of a highly available environment. It maintains the standby databases as transaction- consistent copies of the primary database.  These instances can be placed in several availability zones.Then, if the production database becomes unavailable because of a planned or an unplanned outage of this instance or of the full availability zone, Data Guard can switch any standby database to the production role, minimizing the downtime associated with the outage.  It has three protection modes allowing the customers to maximize protection, availability or performance. The Active Data Guard module enables read-only access to the standby databases, thereby allowing customers to run read queries and reports on the standby instances, and to perform the backups from a standby instance.

You can have zero data loss by using the appropriate data protection mode:

http://docs.oracle.com/cd/B28359_01/server.111/b28294/protection.htm#CHDEDGIF